Multi-Element ICP-MS Profiling of Bushfire Smoke Preparations for Composition-Based Exposure Characterization

Wildfire smoke contains complex mixtures of inorganic and organic species, yet metals in experimental smoke preparations are rarely quantified in a manner directly useful for toxicology. Here, an inductively coupled plasma–mass spectrometry (ICP-MS) workflow for multi-element analysis of bushfire smoke preparations was explored for use in future cell-based studies. The novel contribution is the integration of matrix-matched blank correction, near-LOD handling, micromolar unit conversion and multivariate visualisation into a reproducible workflow for preparation-specific smoke exposure characterisation. This study is an analytical-methods contribution that provides composition-based exposure-characterisation inputs for future toxicological and risk-assessment studies, rather than a direct assessment of biological toxicity or health risk. Eight case-study preparations were analysed: two laboratory-generated bushfire smoke stock solutions (BF#1, BF#2); four laboratory bushfire smoke filter extracts with dominant vegetation types of Eucalyptus, Pine, Banksia, and Mallee; and paired blue gum smoke chamber T- and G-phase samples, each with matched blanks. The workflow combined blank mapping and subtraction, handling of values near the limit of detection, and conversion of concentrations to blank-corrected micromolar units in analytical extracts. Major ions (Na, K, Ca, Mg, P, S) dominated the metal burden, redox-active metals (Al, Mn, Fe, Cu, Zn) were present at sub- to low-micromolar levels, and toxic metals (Pb, Cd) were generally low, with Pb elevated in one filter extract. Silicon was negligible in stock and chamber samples but high in filter extracts, consistent with quartz filter contributions. Heatmaps, burden indices and principal component analysis provided illustrative views of between-sample differences. This workflow enables high-quality single-sample metal characterization and supports more transparent interpretation of wildfire smoke toxicology studies.